forked from Minki/linux
2c419bdeca
The fixmap code from x86 allows us to have compile time virtual addresses that we change the physical addresses of at run time. This is useful for applications like kmap_atomic, PCI config that is done via direct memory map, kexec/kdump. We got ride of CONFIG_HIGHMEM_START as we can now determine a more optimal location for PKMAP_BASE based on where the fixmap addresses start and working back from there. Additionally, the kmap code in asm-powerpc/highmem.h always had debug enabled. Moved to using CONFIG_DEBUG_HIGHMEM to determine if we should have the extra debug checking. Signed-off-by: Kumar Gala <galak@kernel.crashing.org> Signed-off-by: Paul Mackerras <paulus@samba.org>
139 lines
3.4 KiB
C
139 lines
3.4 KiB
C
/*
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* highmem.h: virtual kernel memory mappings for high memory
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*
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* PowerPC version, stolen from the i386 version.
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*
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* Used in CONFIG_HIGHMEM systems for memory pages which
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* are not addressable by direct kernel virtual addresses.
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*
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* Copyright (C) 1999 Gerhard Wichert, Siemens AG
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* Gerhard.Wichert@pdb.siemens.de
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*
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*
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* Redesigned the x86 32-bit VM architecture to deal with
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* up to 16 Terrabyte physical memory. With current x86 CPUs
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* we now support up to 64 Gigabytes physical RAM.
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*
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* Copyright (C) 1999 Ingo Molnar <mingo@redhat.com>
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*/
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#ifndef _ASM_HIGHMEM_H
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#define _ASM_HIGHMEM_H
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#ifdef __KERNEL__
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <asm/kmap_types.h>
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#include <asm/tlbflush.h>
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#include <asm/page.h>
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#include <asm/fixmap.h>
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extern pte_t *kmap_pte;
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extern pgprot_t kmap_prot;
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extern pte_t *pkmap_page_table;
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/*
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* Right now we initialize only a single pte table. It can be extended
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* easily, subsequent pte tables have to be allocated in one physical
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* chunk of RAM.
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*/
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#define LAST_PKMAP (1 << PTE_SHIFT)
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#define LAST_PKMAP_MASK (LAST_PKMAP-1)
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#define PKMAP_BASE ((FIXADDR_START - PAGE_SIZE*(LAST_PKMAP + 1)) & PMD_MASK)
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#define PKMAP_NR(virt) ((virt-PKMAP_BASE) >> PAGE_SHIFT)
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#define PKMAP_ADDR(nr) (PKMAP_BASE + ((nr) << PAGE_SHIFT))
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extern void *kmap_high(struct page *page);
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extern void kunmap_high(struct page *page);
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static inline void *kmap(struct page *page)
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{
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might_sleep();
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if (!PageHighMem(page))
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return page_address(page);
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return kmap_high(page);
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}
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static inline void kunmap(struct page *page)
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{
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BUG_ON(in_interrupt());
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if (!PageHighMem(page))
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return;
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kunmap_high(page);
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}
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/*
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* The use of kmap_atomic/kunmap_atomic is discouraged - kmap/kunmap
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* gives a more generic (and caching) interface. But kmap_atomic can
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* be used in IRQ contexts, so in some (very limited) cases we need
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* it.
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*/
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static inline void *kmap_atomic_prot(struct page *page, enum km_type type, pgprot_t prot)
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{
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unsigned int idx;
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unsigned long vaddr;
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/* even !CONFIG_PREEMPT needs this, for in_atomic in do_page_fault */
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pagefault_disable();
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if (!PageHighMem(page))
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return page_address(page);
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idx = type + KM_TYPE_NR*smp_processor_id();
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vaddr = __fix_to_virt(FIX_KMAP_BEGIN + idx);
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#ifdef CONFIG_DEBUG_HIGHMEM
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BUG_ON(!pte_none(*(kmap_pte-idx)));
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#endif
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set_pte_at(&init_mm, vaddr, kmap_pte-idx, mk_pte(page, prot));
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flush_tlb_page(NULL, vaddr);
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return (void*) vaddr;
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}
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static inline void *kmap_atomic(struct page *page, enum km_type type)
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{
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return kmap_atomic_prot(page, type, kmap_prot);
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}
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static inline void kunmap_atomic(void *kvaddr, enum km_type type)
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{
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#ifdef CONFIG_DEBUG_HIGHMEM
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unsigned long vaddr = (unsigned long) kvaddr & PAGE_MASK;
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enum fixed_addresses idx = type + KM_TYPE_NR*smp_processor_id();
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if (vaddr < __fix_to_virt(FIX_KMAP_END)) {
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pagefault_enable();
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return;
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}
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BUG_ON(vaddr != __fix_to_virt(FIX_KMAP_BEGIN + idx));
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/*
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* force other mappings to Oops if they'll try to access
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* this pte without first remap it
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*/
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pte_clear(&init_mm, vaddr, kmap_pte-idx);
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flush_tlb_page(NULL, vaddr);
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#endif
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pagefault_enable();
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}
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static inline struct page *kmap_atomic_to_page(void *ptr)
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{
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unsigned long idx, vaddr = (unsigned long) ptr;
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pte_t *pte;
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if (vaddr < FIXADDR_START)
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return virt_to_page(ptr);
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idx = virt_to_fix(vaddr);
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pte = kmap_pte - (idx - FIX_KMAP_BEGIN);
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return pte_page(*pte);
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}
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#define flush_cache_kmaps() flush_cache_all()
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#endif /* __KERNEL__ */
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#endif /* _ASM_HIGHMEM_H */
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